Gas turbine metering valve

ABSTRACT

A metering valve for industrial gas turbine engines includes a valve body, a flow tube, an orifice plate, a central flow body, and a mover. The valve body has an inlet and an outlet. The flow tube is carried for axial movement in slidable and sealing engagement with the valve body at an inlet end and an outlet end. The orifice plate has an outlet. The central flow body is provided on an upstream end of the orifice plate and has an annular seal configured to seat into engagement with the outlet end of the flow tube when the flow tube is moved to a downstream position. The central flow body also includes a central, protruding flow diverter upstream and central of the annular seal. The mover is provided in the valve body and is configured to carry the flow tube for displacement of the output end toward and away from the central flow body.

TECHNICAL FIELD

[0001] The present invention pertains to fuel delivery valves. Moreparticularly, the present invention relates to fuel metering valves thatregulate delivery of fuel to a turbine engine.

BACKGROUND OF THE INVENTION

[0002] Liquid and gas fuel metering valves have been used for a numberof industrial turbine engine applications. For example, liquid fuelmetering valves have been used in numerous marine applications.

[0003] In another case, gas fuel metering valves have been coupled withindustrial turbine engines. For example, VG Series gas fuel meteringvalves such as the VG1.5, sold by Precision Engine Controls Corporationof San Diego, Calif., assignee of the present invention, have a balanceddesign with a single moving part. However, the gas flow path thatextends through such valves deviates substantially from a linear flowpath, requiring fuel to transit laterally around 90° lateral cornerswhich reduces efficiency and performance.

[0004] Applications for such fuel metering valves are present in thepower industry for generating electrical power with gas turbine engines,for implementation on offshore oil rigs for power generation, on turbineengines in marine applications such as on hovercraft, and in thepipeline industry for related gas turbine engine applications requiringprecise fuel metering.

[0005] Many fuel metering techniques require the use of a Coriolis flowmeter in combination with a metering valve. However, these flow metersare very expensive and cost-prohibitive for many applications and uses.

[0006] Accordingly, improvements are needed to increase controllableflow accuracy and efficiency from a fuel metering valve to a gas turbineengine, and to reduce cost of implementation. Additionally, improvementsare needed in order to easily reconfigure a fuel metering valve tooptimize the accuracy and efficiency of fuel delivery over varyingranges of supply pressure. Even furthermore, improvements are needed inthe manner in which a fuel metering valve is controlled in order todeliver a desired flow rate of fuel without requiring the utilization ofa separate flow meter which can significantly increase cost andcomplexity.

SUMMARY OF THE INVENTION

[0007] A gas turbine valve is provided having a coaxial valveconstruction with a displacement sensor for detecting position of a flowtube and an orifice plate assembly that cooperates with the flow tube totailor flow rate through the valve by adjusting the displacement of theflow tube relative to the flow diverter.

[0008] According to one aspect, a metering valve for industrial gasturbine engines includes a valve body, a flow tube, an orifice plate, acentral flow body, and a mover. The valve body has an inlet and anoutlet. The flow tube is carried for axial movement in slidable andsealing engagement with the valve body at an inlet end and an outletend. The orifice plate has an outlet. The central flow body is providedon an upstream end of the orifice plate and has an annular sealconfigured to seat into engagement with the outlet end of the flow tubewhen the flow tube is moved to a downstream position. The central flowbody also includes a central, protruding flow diverter upstream andcentral of the annular seal. The mover is provided in the valve body andis configured to carry the flow tube for displacement of the output endtoward and away from the central flow body.

[0009] According to another aspect, a gas turbine metering valveincludes a valve body, a flow tube, a central flow body, a mover, and adisplacement sensor. The valve body has an inlet and an outlet. The flowtube is carried for axial movement in sliding and sealing engagement atan inlet end with the body inlet and at an outlet end with the bodyoutlet. The central flow body has a circumferential seal configured toseat in engagement with the output end of the flow tube. The mover isprovided in the valve body and is configured to carry the flow tube foraxial movement to position the output end toward and away from thecentral flow body to adjust flow capacity through the valve. Thedisplacement sensor is configured to detect axial positioning of theflow tube relative to the central flow body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

[0011]FIG. 1 is an isometric view of a metering valve provided in anapplication environment for delivering fuel at a controlled rate to agas turbine engine, according to one aspect of the invention;

[0012]FIG. 2 is an exploded isometric view of the metering valveillustrated in FIG. 1 depicting assembly and placement of internalcomponents;

[0013]FIG. 3 is a partial breakaway isometric view of the metering valveof FIGS. 1-2 taken along line 3-3 of FIG. 10, with the metering valvepositioned upside down and viewed relative to an outlet end;

[0014]FIG. 4 is an enlarged perspective view from the encircled region 4of FIG. 3 further illustrating cooperation of the flow tube and orificeplate assembly in metering fuel delivery therethrough;

[0015]FIG. 5 is a partial breakaway isometric view of the metering valveof FIGS. 1-2 taken along line 5-5 of FIG. 10, with the metering valvepositioned upside down and viewed relative to an inlet end;

[0016]FIG. 6 is an enlarged perspective view from the encircled region 6of FIG. 5 depicting the displacement sensor and the spring for axiallybiasing the flow tube within the metering valve of FIGS. 1-5;

[0017]FIG. 7 is a centerline sectional view taken along line 7-7 of FIG.10 illustrating the internal construction of the metering valve;

[0018]FIG. 8 is a plan view taken from above the metering valve of FIGS.1-7;

[0019]FIG. 9 is a front elevational view taken relative to FIG. 8further illustrating the metering valve housing assembly;

[0020]FIG. 10 is a right-side view of the metering valve of FIGS. 8 and9 illustrating an outlet end of the metering valve and valve housingassembly;

[0021]FIG. 11 is an alternative construction orifice plate assemblyincluding a different flow diverter than that depicted in FIG. 4, andcorresponding with the encircled region 4 of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] This disclosure of the invention is submitted in furtherance ofthe constitutional purposes of the U.S. Patent Laws “to promote theprogress of science and useful arts” (Article 1, Section 8).

[0023] Reference will now be made to a preferred embodiment ofApplicants' invention. An exemplary implementation is described belowand depicted with reference to the drawings comprising a fuel meteringvalve for delivering fuel to industrial gas turbine engines. A firstembodiment is shown and described below in a configuration withreference generally to FIGS. 1-11. While the invention is described byway of a preferred embodiment, it is understood that the description isnot intended to limit the invention to this embodiment, but is intendedto cover alternatives, equivalents, and modifications which may bebroader than this embodiment such as are defined within the scope of theappended claims.

[0024] In an effort to prevent obscuring the invention at hand, onlydetails germane to implementing the invention will be described in greatdetail, with presently understood peripheral details being incorporatedby reference, as needed, as being presently understood in the art.

[0025] A preferred embodiment metering valve in accordance with theinvention is described with reference to FIGS. 1-11 and is identified byreference numeral 10. Such a metering valve 10 is particularly suitedfor use with industrial gas turbine engines. FIG. 11 illustrates acomponent variation for metering valve 10 that is optimized fordifferent flow rates.

[0026] As shown in FIG. 1, metering valve 10 is configured to provideflow control, contamination resistance, and precision control over awide flow range and within a relatively compact package size. Themetering valve is also configured for use with high-performance,low-emissions, industrial gas turbines that require more than justreliable fuel control in order to optimize gas turbine enginefunctionality. Such applications demand stable, fast, and accurate fuelflow control for a variety of supply pressures and gases.

[0027] In order to achieve this result, metering valve 10 is configuredwith a valve housing 11 that is formed by an electronics enclosureassembly 12 and a valve body assembly 14 that are secured together byfasteners (see hollow bolt 206 in FIG. 7). According to oneconstruction, housing 11 is formed from 6061-T6 aluminum alloy.Additionally, housing assembly 11 includes various O-ring seals 178,180, 182, 184 and 186, as shown in FIGS. 3, 5 and 7. Metering valve 10is mated in sealed engagement with an inlet supply pipe 16 and an outletsupply pipe 18 to deliver fuel from inlet supply pipe 16 in a meteredand precisely controlled manner out through outlet supply 18 to aturbine engine (not shown) where it is combusted. Inlet supply pipe 16is secured with fasteners (not shown) through a mounting end plate at aflow inlet 20, whereas outlet supply pipe 18 is affixed to meteringvalve 10 via an end plate 42 using similar threaded fasteners, such asindividual hex head bolts 40. Outlet supply pipe 18 is secured insealing engagement with a flow outlet 22 of metering valve 10.

[0028] It is understood that inlet supply pipe 16 has an end plate thatis similar to end plate 42 of outlet supply pipe 18, and is secured withfasteners similar to threaded bolts 40 which are received withinthreaded bores 44 of an outlet end plate 28. In the case of flow inlet20, inlet supply pipe 16 secures with threaded fasteners using a similarend plate within threaded bores 43 (see FIG. 5). It is furtherunderstood that each end plate includes a circumferential groove thatextends about the respective flow inlet or outlet into which an O-ringis received for sealing and mating engagement between the respective endplate and an orifice plate assembly 52 (in the case of outlet supplypipe 18) and a corresponding circumferential portion of inlet end plate26 (in the case of inlet supply pipe 16).

[0029] Valve body assembly 14 includes a cylindrical valve housing 24 towhich inlet end plate 26 and outlet end plate 28 are each affixed atopposite ends using a plurality of threaded, high-strength steel, doublehex bolts (or fasteners) 38. Fasteners 38 are preferably equally spacedapart about the circumference of each end plate 26 and 28. Acorresponding end portion at each end of valve housing 24 includescomplementary, corresponding threaded bores configured to receivefasteners 38. Each end plate 26 and 28 includes a plurality of bores(not shown) that extend completely through the end plate, and are sizedto receive each fastener 38 therethrough for threaded engagement withinvalve housing 24, such as into a respective, threaded aperture 86.

[0030] Electronics enclosure assembly 12 includes an electronics housing30 which is fastened to valve housing 24 using hollow bolts 204 and 206(as shown in FIG. 7) and a plurality of threaded cap screws (orfasteners) not shown. A cover 32 is affixed atop electronics housing 30for encasing electronics therein, including electronics that accuratelycontrol flow rate through metering valve 10. More particularly, aplurality of threaded cap screws (or fasteners) 36 are used to securecover 32 atop electronics housing 30. Similarly, each cap screw 36 ispassed through a through-bore within cover 32 and into a threaded bore104 within a topmost edge of electronics housing 30 where such fastenersare threadingly received to retain cover 32 atop electronics housing 30.Further details of enclosure assembly 12 are shown in FIGS. 8-10.

[0031] Electronics housing 30 also includes a conduit hole 34 throughwhich a turbine engine explosion-proof conduit is passed therethrough.Conduit hole 34 comprises a ¾″ NTP thread. As shown in FIG. 3, anexplosion-proof conduit fitting (or union) 35 is threaded into hole 34.More particularly, an explosion-proof wire harness or conduit is passedthrough conduit hole 34 and fitting 35, after which fitting 35 is pottedwith a sealing cement and filler so as to make conduit hole 34 explosionproof and sealed as the conduit passes therethrough. One form of sealingcement for use in fitting 35 comprises Kwik Cement, sold by AppletonElectric Company, 1701 West Wellington Avenue, Chicago, Ill. 60657. Oneform of explosion-proof conduit fitting comprises a UNY or UNF union,also sold by Appleton Electric Company, 1701 West Wellington Avenue,Chicago, Ill. 60657.

[0032] Electronics housing 30 of metering valve 10 is constructed as anexplosion-proof housing having flame paths. U.S. Pat. No. 6,392,322 toMares, et al., issued May 21, 2002 and assigned to the present assignee,teaches one suitable technique for providing flame paths in anexplosion-proof housing. Such construction techniques are also usedherein in order to achieve an explosion-proof electronics housing 30that is suitable for use in a potentially explosive user environment.Accordingly, U.S. Pat. No. 6,392,322 to Mares, et al. is hereinincorporated by reference.

[0033] Also shown in FIG. 1, a metal name plate 46 is secured atop cover32 using a plurality of threaded drive screws 48. Product informationfor metering valve 10 is then printed on or etched into name plate 46.Furthermore, a threaded ground hole 50 is also provided within a sidewall of electronics housing 30 into which a threaded fastener and aground strap can be attached thereto for grounding the housing ofmetering valve 10. Preferably, ground hole 50 does not pass completelythrough the side wall of electronics housing 30.

[0034] According to FIG. 2, metering valve 10 is shown in an explodedview to further facilitate understanding of the construction andoperation of components contained therein. More particularly, meteringvalve 10 provides a stable, fast and accurate fuel flow control systemextending over a range of supply pressures and gases. Because of theparticular design of metering valve 10, a flow-through design isprovided that is capable of automatically compensating for variations inpressure and temperature in order to provide precise fuel flow requiredfor specific gas turbine conditions under which the turbine and valvemust operate. The electronics assembly includes a determination of fuelflow measurement based on valve feedback derived from pressure,temperature and displacement sensors in the valve. The valve isprogrammable for flow versus demand and complete closed-loop fuelcontrol is made possible when using particular interface features.Accordingly, metering valve 10 is capable of being programmable for flowversus demand.

[0035] Metering valve 10 provides a smooth flow-through design by way ofan orifice plate assembly 52 that is carried in outlet end plate 28 byway of a female threaded bore 74 (see FIG. 2) including female threadedportion 192 (see FIG. 4). An axial mover 56 comprising a linear motor 58supports and moves a central cylindrical flow tube 60 toward and awayfrom orifice plate assembly 52 in order to regulate flow through theorifice plate assembly 52. By moving flow tube 60 into engagement with aseal 82 on orifice plate assembly 52, flow is completely stopped atorifice plate assembly 52, and flow outlet 22 is completely closed. Byactuating linear motor 58 to move flow tube 60 towards an upstreamposition away from orifice plate assembly 52, an annular gap 136 (seeFIG. 3) is formed between the downstream end of flow tube 60 and seal 82of orifice plate assembly 52.

[0036] In operation, the flow rate of fuel can be controlled byprecisely positioning flow tube 60 relative to orifice plate assembly52. The relative position of the downstream end of flow tube 60 andorifice plate assembly 52 can be varied by accurately positioning flowtube 60 relative thereto. Additionally, flow is tailored based upon thespecific axial and radial geometry provided on a flow diverter 78 oforifice plate assembly 52. Flow diverter 78 extends upstream and withinflow tube 60 so as to vary the dimension of the annular gap 136 (seeFIG. 3) formed therebetween for various positions of the downstream endof flow tube 60 relative to orifice plate assembly 52.

[0037] As shown in FIG. 2, orifice plate assembly 52 comprises acylindrical orifice plate 76 that includes three crescent-shaped flowapertures 84 that are spaced radially about orifice plate 76. Accordingto such construction, orifice plate 76 comprises a spider in which threeflow apertures 84 are provided between the spokes of such spider.Orifice plate 76 includes a plurality of male threads adjacent anupstream edge that mate in threading engagement within a threaded bore74 of outlet end plate 28. A radial outermost portion of orifice plate76 is received within a complementary bore 72 of outlet end plate 28.According to one construction, orifice plate 76 is made from Nitronic™50, a version of 316 stainless steel (SS).

[0038] One desirable feature of the present invention is provided by theability to replace flow diverter 78 with an alternative flow diverterhaving a different axial profile (see FIG. 11) by removing threadedfastener 80 which retains flow diverter 78 onto orifice plate 76.Subsequently, a new, alternatively constructed flow diverter can bemounted upstream and onto orifice plate 76 by re-inserting threadedfastener 80 and threading such flow diverter into engagement therewith.Hence, sensitivity of metering valve 10 can be optimized for differentranges of flow rates by substituting in an optional flow diverter havinga desired shape.

[0039] Linear motor 58 of FIG. 2 includes a motor housing 70 from whicha pair of solenoid wires 66 and 68 extends for connection withcorresponding electronics within electronics enclosure assembly 12. Acircumferential shoulder 62 is rigidly secured to a location on flowtube 60. Shoulder 62 helps retain an armature 64 at a precise locationalong flow tube 60. Linear motor 58, in assembly, is received within aninternal bore 100 of valve housing 24.

[0040] In assembly, the double hex bolts 38 extend through outlet endplate 28 and into complementary, corresponding threaded apertures 86 ata downstream end of valve housing 24. Similarly, double hex bolts 38extend through corresponding apertures in inlet end plate 26 and intothreaded apertures in an upstream end of valve housing 24 (similar tothreaded apertures 86 provided at a downstream end of valve housing 24,but not shown).

[0041] Inlet end plate 26, as shown in FIG. 2, is likewise affixed to anupstream end of valve housing 24 using a plurality of threaded doublehex bolts 38. Inlet end plate 26 is configured to support a displacementsensor 88, a temperature inlet sensor 94, and an inlet pressure sensor96. According to one construction, displacement sensor 88 comprises alinear variable differential transformer (LVDT) 90 that is carried by anLVDT support plate 92. According to one construction, temperature inletsensor 94 comprises a thermistor. Similarly, an outlet pressure sensor98 is carried on an inner surface of outlet end plate 28.

[0042] According to one suitable construction, LVDT 90 is a model MHRSchaevitz LVDT sensor sold by Measurement Specialties, Inc. (MSI), 710Route 46 East, Ste. 206, Fairfield, N.J. 07004. Similarly, temperatureinlet sensor 94 comprises a Model H-025-08-1 (Part No. 10K3D612)thermistor sold by BetaTHERM of Shrewsbury, Mass., and headquartered inGalway, Ireland. Furthermore, pressure sensors 96 and 98 each comprise aModel 85 Ultra Stable™ stainless steel pressure sensor manufactured andsold by Measurement Specialties, Inc. (MSI), 710 Route 46 East, Ste.206, Fairfield, N.J. 07004.

[0043]FIG. 2 also illustrates the detailed construction and assembly ofelectronics enclosure assembly 12 which is secured atop valve bodyassembly 14 to form a valve housing assembly 11. As shown in FIGS. 2,and 7, electronics housing 30 is configured to form a substantiallyrectangular electronics cavity 102 within assembly 12. An electronicspackage 101 is physically attached to a bottom surface of electronicscavity 102 using four threaded fasteners 110 that are threaded intoengagement with female threads provided within corresponding standoffs118 that are threaded into the bottom surface of electronics cavity 102.

[0044] More particularly, electronics package 101 includes a motordriver printed circuit (PC) board 112 and a digital logic printedcircuit (PC) board 116. Boards 112 and 116 are carried in spaced-apartrelation using a plurality of tubular spacers 114 that are placed incoincidence within apertures at each of the four corners of each board112 and 116 and configured to receive threaded fasteners 110therethrough and into standoffs 118. Standoffs 118 are first securedwithin threaded female apertures within a bottom surface of electronicscavity 102. Standoffs 118 further include female threads sized toreceive fasteners 110 at a topmost end for securing electronics package101 within electronics cavity 102. Board 112 includes a pair of customerconnectors 120 and 122 which will be discussed in greater detail below.Electronics 124 are provided on board 112. Processing circuitry 126 isprovided on both boards 112 and 116. Additionally, a pair of powereddiode wires 128 and 130 are provided.

[0045] Upon mounting electronics package 101 within electronics cavity102, cover 32 is then secured atop housing 30 using a plurality ofthreaded cap screws 36 which are received through respective clearancethrough-bores 132 and cover 32. To facilitate sealing engagement ofcover 32 to housing 30, an O-ring seal 108 is provided within acomplementary receiving groove on the bottom of cover 32 positioned tomate with a top sealing surface 106 provided on housing 30 inboard ofthreaded bores 104 that receive threaded portions of cap screws 36, inassembly.

[0046] To complete assembly, product name plate 46, including productand manufacturing information printed or embossed thereon, is affixedatop cover 32 using a plurality of drive screws 48 that pass throughholes 54 in plate 46 for threaded securement within correspondingthreaded holes 55 provided in corresponding locations of cover 32.

[0047] Upon assembly, metering valve 10 of FIG. 2 is configured toreceive fuel into flow inlet 20, meter such fuel by axially positioningflow tube 60 relative to seal 82 and flow diverter 78 of orifice plateassembly 52, and deliver fuel at a desired rate to a gas turbine enginevia three flow apertures 84 that provide flow outlet 22. The fuel can begas or liquid. Optimally, the metering valve can be used to deliver amixture of fuel and air.

[0048] According to FIG. 3, a flow tube assembly 134 within meteringvalve 10 provides for precision fuel flow control over a wide flow rangeand within a very compact package size through axial displacement offlow tube 60 relative to seal 82 and flow diverter 78 of orifice plateassembly 52. By properly energizing wire windings 176 of motor windingassembly 172, electromagnetic force (EMF) lines of flux attract anarmature 64 of flow tube assembly 134 towards a pole piece 162. Byadjusting the duty cycle to wire windings 176, the position of armature64 (as well as tube 60) can be varied such that a frustoconical portionof armature 64 is moved closer towards pole piece 162, therebycompressing coil spring 142. When windings 176 are not energized, coilspring 142 drives flow tube 60 into sealing engagement with seal 82 oforifice plate assembly 52, thereby completely shutting off flow throughmetering valve 10.

[0049] As shown in FIG. 3, armature 64 has a frustoconical portion thatis shaped in complementary relation with pole piece 162 such thatmaximum attraction of pole piece 162 brings pole piece 162 intoproximate nesting relation with the complementary frustoconical portionof armature 64, thereby moving flow tube 60 away from seal 82 so as toimpart a maximum open dimension for flow gap 136. According to onedesign, flow gap 136 has a maximum valve of one-quarter inch.

[0050] According to one construction, motor winding assembly 172comprises a bobbin case 174 about which a 17-gauge wire is wound so asto provide wire windings 176. Motor winding assembly 172, whenenergized, generates electromagnetic force (EMF) lines of flux thatattract armature 64 and compress spring 142 as wire windings 176 receivean adjusted level of current using a current control loop so as toadjust a duty cycle therethrough. The presence of wire windings 176between motor housing 70 and pole piece 162 cooperates with armature 64so as to provide appropriate lines of flux to attract the armature 64 topole piece 162.

[0051] In order to determine the relative position of flow tube 60 andthe width of circumferential flow gap 136, a displacement sensor 88 inthe form of LVDT 90 detects the position of flow tube 60 relative toinlet end plate 26 in valve housing 24. Such relative displacementcorresponds with the displacement of flow tube 60 relative to orificeplate 76 which corresponds with the dimension of flow gap 136.Accordingly, fuel is precisely delivered at a desired flow rate by wayof flow inlet 20 to flow tube 60 and out through three flow apertures 84that are provided through orifice plate 76, as flow tube 60 is spacedaway a desired distance from seal 82 via actuation of linear motor 58corresponding with a specific duty cycle being delivered to wirewindings 176.

[0052] As shown in FIGS. 3 and 5, LVDT 90 comprises a mechanicallyactuated core 166 that is carried by support plate 92 in fixed relationwith flow tube 60. Accordingly, movement of flow tube 60 can be detectedby movement of plate 92 and core 166 relative to coils within acylindrical coil assembly (or transformer) 168. Movement of themechanically actuated core 166 relative to assembly 168 changesreluctance of a flux path between a primary coil and a secondary coil ofassembly 168, thereby generating an output signal related todisplacement of flow tube 60. It is further understood that circuitry isprovided for interfacing with LVDT sensor 90 within circuitry providedin electronics package 101 (of FIG. 2).

[0053] As shown in FIGS. 3 and 5, in operation, displacement sensor 88is configured to detect axial positioning of flow tube 60 relative to acentral flow body provided by flow diverter 78 and seal 82 of orificeplate assembly 52. Fuel which is received upstream via flow inlet 20passes downstream through flow tube 60, out and around circumferentialflow gap 136, and out through three arcuate, circumferentiallyspaced-apart flow apertures 84 within orifice plate 76. Fuel leavingthrough flow apertures 84 thereby provide for flow outlet 22.Subsequently, the precisely metered fuel is delivered to an outletsupply pipe, such as outlet supply pipe 18 depicted in FIG. 1.

[0054] According to FIGS. 3 and 4, flow diverter 78 is shaped the shapecan determine the outlet characteristics, such as flow resolution,provided between flow tube 60, flow diverter 78, and seal 82 as fuel isdelivered through flow apertures 84 into flow outlet 22. As shown inFIG. 4, a threaded fastener 80, along with a lock washer 188, isreceived within an enlarged, recessed bore 191, a clearance bore 190,and into a threaded bore 189 that is provided within flow diverter 78.Securement of threaded fastener 80 into threaded bore 189 retains flowdiverter 78 onto orifice plate 76. An elevated shoulder 193 is providedin flow diverter 78 and sized sufficiently to securely retain seal 82 insealing engagement between flow diverter 78 and orifice plate 76 asfastener 80 is secured into flow diverter 78. Such construction enablesa user to easily clean the valve and to change the shape of flowdiverter 78. For example, alternatively-shaped flow diverter 1078 (seeFIG. 11) can be substituted for flow diverter 78.

[0055] As shown in FIGS. 3 and 5, flow tube 60 is carried for axialmovement by linear motor 58 in slidable and sealing engagement at theinput end and the output end with inlet end plate 26 and outlet endplate 28 of valve body assembly 14, respectively. More particularly, adynamic seal 152 is provided adjacent the downstream end of flow tube60, as shown in FIGS. 3 and 4. According to one construction, dynamicseal 152 is formed from a filled polytetrafluoroethylene (PTFE).Adjacent an upstream seal 152, a circumferential bearing 154 isprovided. According to one construction, bearing 154 comprises a Rulon™J bearing. Bearing 154 facilitates axial fore and aft movement of flowtube 60 relative to outlet end plate 28; whereas seal 152 provides asliding seal along the downstream end of flow tube 60 relative to outletend plate 28.

[0056] Similarly, FIGS. 5 and 6 further illustrate the seal and supportcomponents provided for flow tube 60 relative to inlet end plate 26.More particularly, a wiper seal 156 is provided adjacent an upstream endof flow tube 60 so as to provide a wiping seal between flow tube 60 andinlet end plate 26. Additionally, a dynamic seal 158 is provideddownstream of wiper seal 156 to further facilitate a dynamic sealbetween flow tube 60 and inlet end plate 26. Furthermore, acircumferential bearing 160 is provided downstream of dynamic seal 158,between flow tube 60 and inlet end plate 26. Bearing 160 provides asliding bearing surface to facilitate axial fore and aft motion of flowtube 60 relative to inlet end plate 26. According to one construction,dynamic seal 158 comprises a filled polytetrafluoroethylene (PTFE).According to one such construction, bearing 160 also comprises a Rulon™J bearing.

[0057]FIG. 4 illustrates in greater detail the removable and sealingmounting features of orifice plate assembly 52 in outlet end plate 28.More particularly, orifice plate 76 has a circumferential outer diameterthat is received in a complementary cylindrical bore 196 within outletend plate 28. Orifice plate 76 includes a stepped-down diameter portioncomprising a male threaded shoulder 194. Threaded shoulder 194 isthreaded into engagement within complementary, corresponding femalethreaded bore 192 within outlet end plate 28. A perpendicularcircumferential face 198 is provided between cylindrical bore 196 andthreaded bore 192. A groove in face 198 is configured to receive acylindrical O-ring 178 that provides a seal between orifice plate 76 andoutlet end plate 28.

[0058] The ability to mate and demate orifice plate assembly 52 withoutlet end plate 28 facilitates inspection, cleaning, and maintenance ofrespective components including seal 152, flow diverter 78, and seal 82.Additionally, one feature of the present invention entails changing thegeometric configuration of flow diverter 78 by replacing flow diverter78 with an alternatively constructed and configured flow diverter, suchas flow diverter 1078 as shown with reference to FIG. 11 and describedin greater detail below.

[0059] As shown in FIGS. 3, 5 and 6, coil spring 142 is received withina cylindrical groove 170. As shown in FIG. 6, once flow tube 60 is movedto a maximum open-valve position for the metering valve, support plate92 compresses spring 142 within cylindrical groove 170 to a maximumcompressive position. Corresponding with such position, displacementsensor 88, here LVDT 90, detects such maximum open position by way ofcore 166 being displaced maximally within cylindrical coil assembly (ortransformer) 168. When the flow tube is moved to a closed position forthe valve assembly, plate 92 moves in a downstream direction as themotor is de-energized, thereby enabling coil spring 142 to drive flowtube 60 to a downstream position as plate 92 (which is circumferentiallyaffixed to flow tube 60) pushes flow tube 60 into sealing and seatingengagement with seal 82 (see FIG.4) at an opposite end. Hence, coilspring 142 ensures closure of the valve assembly when the linear motoris not energized. Hence, further benefit is provided in that the valveis closed when power is lost to the drive motor.

[0060] As shown in FIGS. 3, 5 and 7, armature 64 has a cylindricaloutermost portion that is contiguous with a frustoconical portion.However, a downstream end of armature 64 is undercut, as shown in FIGS.3 and 7. Armature 64, as shown in FIG. 7, has female threads 202 thatenable threaded engagement of armature 64 onto flow tube 60 viacomplementary, corresponding male threads 203 that are provided on flowtube 60. A circumferential shoulder 62 on flow tube 60 provides anaffixation stop point for securing armature 64 in threaded engagement ata fixed location along flow tube 60, as shown in FIG. 7.

[0061] Additionally, a circumferential groove 140 is provided on theradial outermost portion of armature 64 (see FIG. 7) into which anO-ring 139 is first provided and on top of which a seal ring 138 isfurther provided. As shown in FIGS. 3, 5 and 7, seal ring 138 forms asliding piston-type seal with a bore 69 provided in motor housing 70.Armature 64 is further secured, after threading, onto flow tube 60 at afixed position using threaded set screw 165 that is received within athreaded set screw hole 164 of armature 64. Set screw 165 is threadedinto screw hole 164 until set screw 165 engages with an outer surface offlow tube 60, thereby fixing armature 64 at a desired location on flowtube 60.

[0062] The provision of seal ring 138 along cylindrical bore 69 providesa further advantage to the present metering valve. According to oneconstruction, seal ring 138 is made of steel. More particularly, sealring 138 provides dampening of flow tube 60 as seal ring 138 and bore 69cooperate to partition a pair of sealed air chambers 215 and 216 (seeFIGS. 3, 5 and 7) downstream and upstream of seal ring 138,respectively. As shown in FIG. 7, movement of armature 64 and seal ring138 within cylindrical bore 69 provides compression and evacuation onrespective opposite sides of seal ring 138 as armature 64 moves so as tochange the relative volumes of air chambers 215 and 216. Such actionimparts dampening to sudden motions of flow tube 60 within the meteringvalve which imparts benefits and stability to fuel flow control by thevalve.

[0063]FIGS. 2 and 7 illustrate the provision of a temperature sensor inthe form of a thermistor 94 which is provided adjacent an inlet (orupstream) end of flow tube 60 for measuring inlet temperature of fuelinto flow tube 60 of metering valve 10. As shown in FIGS. 2 and 7,thermistor 94 is threaded for mounting into a threaded bore 250 providedin inlet end plate 26. As shown in FIG. 7, threaded bore 250 is in fluidcommunication with a temperature port 244 that communicates with anupstream end of flow tube 60 for detecting upstream temperature at flowtube 60. To facilitate manufacturing of temperature port 244, anenlarged port 246 is provided with a threaded female portion forreceiving a threaded plug 148. Plug 148 is used to seal the radial outerend of threaded port 246 and to further facilitate cleaning andmaintenance of port 244. Further close-up details of the position ofinlet pressure sensor 96 relative to pressure port 144 are illustratedin FIG. 6.

[0064] In addition to illustrating the position of thermistor 94 andtemperature port 244, FIGS. 2-3 and 5-7 further illustrate thepositioning of an inlet pressure sensor 96 (see FIGS. 2-3 and 5-7) andan outlet pressure sensor 98 (see FIGS. 2 and 7). The resulting detectedtemperature from thermistor 94 and pressures from pressure sensors 96and 98 are utilized to calculate fuel flow delivery rates throughmetering valve 10 for both sub-sonic and sonic flow conditions.Alternatively, a flow meter can be used to correlate flow rate withpositioning of flow tube 60.

[0065] Inlet pressure sensor 96 is received within a threaded bore 150which communicates via the pressure port 144 with flow inlet 20.Pressure port 144 is formed similar to temperature port 244 wherein anenlarged threaded port 146 is first formed and in which a threaded plug148 is provided to seal threaded port 146 and pressure port 144 afterconstruction.

[0066] Similarly, outlet pressure sensor 98 is threaded into a similarthreaded bore 350 which communicates with a pressure port 344. Anenlarged threaded port 346 is used to facilitate construction ofpressure port 344, after which another threaded plug 148 is threadedinto sealing engagement therein.

[0067] In operation, temperature port 244 enables thermistor 94 todetect inlet temperature of fuel at flow inlet 20. Likewise, pressureport 144 enables inlet pressure sensor 96 to detect pressure of fuel atflow inlet 20. Finally, pressure port 344 enables outlet pressure sensor98 to detect downstream pressure adjacent flow outlet 22, or adjacent tothe downstream end of flow tube 60.

[0068]FIG. 7 illustrates the physical attachment of electronicsenclosure assembly 12 to valve body assembly 14. More particularly, apair of hollow bolts 204 and 206 are used to secure electronicsenclosure assembly 12 to valve body assembly 14. Additionally, hollowbolts 204 and 206 facilitate the passage of wiring from sensors 94, 96and 98 to electronics package 101 within electronics enclosure assembly12. More particularly, wires 208 and 209 pass through hollow bolt 204;whereas wires 210 and solenoid wires 66 and 68 pass through hollow bolt206. Each bolt 204 and 206 includes a circumferential outer groove 213in which a helicoil lock 212 is provided to lock each bolt 204 and 206into the respective threaded surfaces provided in valve housing 24.

[0069] Also shown in FIG. 7, a threaded fastener 214 is used to securemotor housing 70 together with pole piece 162. Two other threadedfasteners 214 are equally spaced circumferentially from threadedfastener shown in FIG. 7.

[0070]FIGS. 8-10 illustrate the general layout of valve housing assembly11 for metering valve 10. As shown in FIG. 8, one exemplary constructionfor metering valve 10 is 6.75 inches deep, which corresponds with thevertical length of cover 30 as shown in FIG. 8. Also according to suchexemplary construction, such valve has a width of 5.8 inches, whichcorresponds with the distance from the outer surfaces of inlet end plate26 and outlet end plate 28. Furthermore, such exemplary valve has aheight, as shown in FIGS. 9 and 10, of 9.1 inches. However, it isunderstood that other constructions and dimensions are possibleaccording to various aspects of the invention.

[0071]FIG. 11 illustrates an alternative configuration orifice plateassembly 1052, similar to orifice plate 52 in FIG. 4, but having analternatively- shaped flow diverter 1078. More particularly, orificeplate 76 carries, by way of threaded fastener 80, flow diverter 1078 onan upstream side of orifice plate 76. As was the case with flow diverter78 in FIG. 4, flow diverter 1078 traps seal 82 in sealing engagementcircumferentially thereabout against orifice plate 76. Fastener 80 isremovably received in secure engagement within complementary threads inflow diverter 1078 and is further locked therein using a lock washer188. Fastener 80 mates with female threads in threaded bore 189 providedin flow diverter 1078. Additionally, an enlarged clearance bore 191 isrecessed into orifice plate 76 to receive the head in flush relationtherein. The provision of flow diverter 1078 provides a modified flowaperture 1084 through orifice plate assembly 1052.

[0072] Comparing flow diverter 78 of FIG. 4 with flow diverter 1078 ofFIG. 11, both flow diverters provide a Rankine half-body of revolution.Flow diverter 78 is configured in the shape of a witch's hat, having aconcave, conical shape. Flow diverter 1078 has a somewhathemispherical-shaped head that is generally convex in shape. [0073] Flowdiverter 78 of FIG. 4 has been found to be optimally suited forincorporation into the present metering valve when the metering valve isused as a main fuel control valve for a gas turbine engine. In contrast,flow diverter 1078 has been found to be ideally suited for incorporationinto the metering valve when the metering valve is used as a pilot fuelcontrol valve for a gas turbine engine. In summary, the ability to varythe configuration of a flow diverter enables reconfiguration of ametering valve to obtain better flow resolution, or area resolution, forparticular applications.

[0073] By way of example, flow diverter 1078 of FIG. 11 is more optimalfor smaller flows of fuel; whereas flow diverter 78 of FIG. 4 is betterfor higher flow rates of fuel.

[0074] As shown in FIGS. 1-11, metering valve 10 uses onboard sensorsand digital electronics to automatically measure and control mass flowof fuel over a wide range of temperatures and pressures. The actual fuelflow can be determined with onboard electronics based on feedbacksignals from sensors in the valve. The metering valve also usesintegrated, 24-volt DC (VDC) digital electronics that contain additionalinputs and outputs for allowing programmable flow control, closed-loopturbine control, and an array of other options. Analog interfaces areprovided within the electronics housing which are user configurable as4-20 mA (current) or 0-5 VDC (voltage). Real-time health and datamonitoring of the metering valve can also be implemented through anisolated RS232/485 serial interface that enables a user to see massflow, inlet and outlet pressures, gas temperature and diagnostics forthe metering valve.

[0075] The flow tube construction for the metering valve is balanced.Additionally, the flow-through construction is self-cleaning. Evenfurthermore, the only moving part present within the valve is the movingcore that is driven by a direct acting solenoid comprising the armatureand flow tube. As a result, prior art techniques of utilizing pneumaticsor hydraulics for actuating a valve are eliminated, and theirconcomitant tendency to leak and break down is eliminated from thedesign. A fail-safe closing spring having an easy-to-clean soft seatprovides a positive, leak-tight shutoff which further enhances thecontamination-resistant design of the metering valve.

[0076] Under experimental tests, it has been determined that the presentmetering valve design results in improved flow performance because ofits smooth, flow-through design. The metering valve has been found tohave a 200:1 turn-down ratio and a plus or minus one percent linearity,making such metering valve ideal for use with 1-10 megawatt gasturbines. Even furthermore, the electronics on the metering valve enablea user to program a maximum flow rate and relatively easily achieve suchresult by way of the incorporated sensors.

[0077] In compliance with the statute, the invention has been describedin language more or less specific as to structural and methodicalfeatures. It is to be understood, however, that the invention is notlimited to the specific features shown and described, since the meansherein disclosed comprise preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

The invention claimed is:
 1. A metering valve for industrial gas turbineengines, comprising: a valve body having an inlet and an outlet; a flowtube carried for axial movement in slidable and sealing engagement withthe valve body at an inlet end and an outlet end; an orifice platehaving an outlet; a central flow body provided on an upstream end of theorifice plate having an annular seal configured to seat into engagementwith the outlet end of the flow tube when the flow tube is moved to adownstream position and a central, protruding flow diverter upstream andcentral of the annular seal; and a mover provided in the valve body andconfigured to carry the flow tube for displacement of the output endtoward and away from the central flow body.
 2. The valve of claim 1wherein the mover comprises an armature carried by the flow tube and asolenoid provided about the armature and electrically communicating withthe armature to move the armature and the flow tube to selected axialpositions.
 3. The valve of claim 1 wherein the annular seal comprises acircumferential seal.
 4. The valve of claim 1 wherein the flow diverterof the orifice plate comprises a convex, leading end nipple.
 5. Thevalve of claim 4 wherein the flow diverter further comprises a concavelip extending circumferentially about the convex nipple.
 6. The valve ofclaim 1 wherein the flow diverter comprises a central flow diverter witha hemispherical head.
 7. The valve of claim 6 wherein the orifice platecomprises an outer mounting ring, the flow body, and a spider carryingthe flow body coaxially within the mounting ring.
 8. The valve of claim7 wherein the orifice plate further comprises a circumferential array offlow apertures provided between adjacent arms of the spider and aboutthe circumferential seal.
 9. The valve body of claim 1 wherein the flowdiverter comprises a Rankine half-body of revolution.
 10. The valve bodyof claim 9 wherein the flow diverter is removably mounted to theupstream end of the orifice plate with a fastener.
 11. A gas turbinemetering valve, comprising: a valve body having an inlet and an outlet;a flow tube carried for axial movement in sliding and sealing engagementat an inlet end with the body inlet and at an outlet end with the bodyoutlet; a central flow body having a circumferential seal configured toseat in engagement with the output end of the flow tube; a moverprovided in the valve body and configured to carry the flow tube foraxial movement to position the output end toward and away from thecentral flow body to adjust flow capacity through the valve; and adisplacement sensor configured to detect axial positioning of the flowtube relative to the central flow body.
 12. The valve of claim 11wherein the central flow body comprises an orifice plate, the flow tubeis a cylindrical tube, and the flow body extends in an upstreamdirection from the orifice plate in axial alignment with the flow tubeto mate and demate with the output end of the flow tube as the flow tubeis moved in upstream and downstream directions, respectively.
 13. Thevalve of claim 11 wherein the central flow body cooperates with theoutput end of the flow tube, when in spaced-apart relation, to provide aflow passage therebetween, wherein volumetric flow capacity of the valveis adjusted by moving the flow tube to a desired position relative tothe flow body to impart a corresponding volumetric flow capacity therebetween.
 14. The valve of claim 11 wherein the displacement sensorcomprises a linear variable differential transformer (LVDT).
 15. Thevalve of claim 11 wherein the linear variable differential transformeris affixed at a first end to the valve body and is affixed at a secondend to the flow tube.
 16. The valve of claim 11 wherein the central flowbody is removably secured in the valve body at the body outlet.
 17. Thevalve of claim 11 further comprising a spring interposed between thevalve body and the flow tube to bias the flow tube at the downstream endfor engagement with the flow body.
 18. The valve of claim 17 wherein themover comprises a linear motor with an armature affixed to the flowtube, a pole piece, and wire windings.
 19. The valve of claim 18 whereinthe wire windings are energized to generate magnetic forces that attractthe armature to move the flow tube upstream and compress the spring. 20.The valve of claim 19 further comprising processing circuitry configuredto control energizing of the wire windings to realize a desired upstreampositioning of the flow tube relative to the central flow body toachieve a desired flow rate through the valve body.